Sarin is a nerve toxin so deadly that just one drop can kill a grown man. The fatality typically comes from cardiac arrest or suffocation, as overstimulated muscles around the heart and lungs eventually seize and stop working altogether.

Those lethally exposed can also foam at the mouth and fall into spasms. With a high enough dose, death can occur in just one minute. Even a low dose can cause permanent neurological damage.

On Tuesday General Itai Brun, chief of the research division of Israel's army intelligence branch, said that Assad deployed chemical weapons against rebel forces outside of Aleppo on March 19. Secretary of Defense Chuck Hagel and Qatari Prime Minister Hamad bin Jassim Al Thani quickly followed Israel with their own accusations.

American intelligence assets on the ground tested blood samples from multiple victims of the attack, and the results were positive for sarin, according to sources of Wired's Danger Room.

Loyd, reporting for the Times from Aleppo, spoke with survivors and doctors who treated the 17 casualties in addition to examining video footage shot in the immediate aftermath of the alleged attacks.

From The Times (emphasis ours):

The Syrian regime prefers to gas its opponents in this small-scale way, testing the elasticity of President Obama’s “red line”, the words Mr. Obama used in August to warn Damascus against the use of chemical weapons. In this way the regime avoids large-scale massacre and allows the West enough room to prevaricate over the issue of intervention.